Golden State Warriors' Patrick McCaw goes up for a shot against Portland Trail Blazers' CJ McCollum in the second quarter during Game 2 of the First Round of the Western Conference 2017 NBA Playoffs at Oracle Arena on Wednesday, April 19, 2017 in Oakland, Calif. less

Golden State Warriors' Patrick McCaw goes up for a shot against Portland Trail Blazers' CJ McCollum in the second quarter during Game 2 of the First Round of the Western Conference 2017 NBA Playoffs at Oracle ... more

Photo: Scott Strazzante / The Chronicle

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OAKLAND, CA - APRIL 19: Damian Lillard #0 of the Portland Trail Blazers goes up for a shot against Patrick McCaw #0 of the Golden State Warriors Game Two of the Western Conference Quarterfinals during the 2017 NBA Playoffs at ORACLE Arena on April 19, 2017 in Oakland, California. NOTE TO USER: User expressly acknowledges and agrees that, by downloading and or using this photograph, User is consenting to the terms and conditions of the Getty Images License Agreement. (Photo by Ezra Shaw/Getty Images) less

OAKLAND, CA - APRIL 19: Damian Lillard #0 of the Portland Trail Blazers goes up for a shot against Patrick McCaw #0 of the Golden State Warriors Game Two of the Western Conference Quarterfinals during the 2017 ... more

Photo: Ezra Shaw, Getty Images

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Golden State Warriors' Patrick McCaw blocks a Portland Trail Blazers' Damian Lillard shot in the third quarter during Game 2 of the First Round of the Western Conference 2017 NBA Playoffs at Oracle Arena on Wednesday, April 19, 2017 in Oakland, Calif. less

Golden State Warriors' Patrick McCaw blocks a Portland Trail Blazers' Damian Lillard shot in the third quarter during Game 2 of the First Round of the Western Conference 2017 NBA Playoffs at Oracle Arena on ... more

Photo: Carlos Avila Gonzalez, The Chronicle

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Golden State Warriors' Patrick McCaw blocks a Portland Trail Blazers' Damian Lillard shot in the third quarter during Game 2 of the First Round of the Western Conference 2017 NBA Playoffs at Oracle Arena on Wednesday, April 19, 2017 in Oakland, Calif. less

Golden State Warriors' Patrick McCaw blocks a Portland Trail Blazers' Damian Lillard shot in the third quarter during Game 2 of the First Round of the Western Conference 2017 NBA Playoffs at Oracle Arena on ... more

Photo: Scott Strazzante, The Chronicle

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Patrick McCaw goes up for a shot against Portland’s Evan Turner in the second quarter during Game 2 at Oracle Arena on Wednesday. McCaw was filling in as a starter for Kevin Durant.

Patrick McCaw goes up for a shot against Portland’s Evan Turner in the second quarter during Game 2 at Oracle Arena on Wednesday. McCaw was filling in as a starter for Kevin Durant.

Photo: Scott Strazzante, The Chronicle

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Warriors’ Patrick McCaw shows aggressiveness in fill-in start

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It didn’t take long for the Warriors to get familiar with Patrick McCaw’s savvy on-court demeanor. In late September, during one of the first practices of training camp, assistant coach Willie Green called him “P-Nice” because the spindly rookie was unfazed against Stephen Curry and Klay Thompson.

The nickname stuck. Over the past seven months, as he became the rare second-round draft pick to contribute in his first NBA season, McCaw made good on his new moniker. The only issue? Often, he was too calm on the court. Open shots were ignored at the risk of hurting Golden State’s offensive flow.

By that measure, McCaw experienced a bit of a breakthrough in Wednesday night’s Game 2 win over Portland. In the second quarter, after teammates encouraged him during a timeout to be more aggressive, he hit a three-pointer from the top of the arc and drove for a layup. McCaw finished with nine points, five rebounds, no turnovers and a plus-27 in 34 minutes, a stat line reminiscent of his mentor, Sixth Man of the Year candidate Andre Iguodala.

It was the type of performance that could make head coach Steve Kerr comfortable continuing to be cautious with Kevin Durant’s strained left calf. Though McCaw can’t be expected to replicate the eight-time All-Star’s production, he is a more capable fill-in starter than when he spelled Durant in the first unit during the regular season.

“The main thing I liked was that he was unafraid,” Kerr said of McCaw in Game 2. “When K.D. comes back, Pat’s probably not going to play a whole lot. But the fact that he stayed prepared and stayed ready, that says a lot.”

Added McCaw: “For my first (start in the playoffs), it was exciting — just knocking down a few shots, making the right play, playing good defense. It was awesome.”

The son of a high school basketball coach, McCaw, 21, has a grasp of the sport’s nuances. Unlike many rookies, who struggle with the speed of the NBA, he generally makes the right reads and thinks a play or two ahead. It was that basketball IQ that allowed McCaw, the No. 38 pick of the 2016 NBA draft out of UNLV, to carve out a rotation spot on the league’s best team.

Two months ago, after Durant suffered a left knee injury at Washington, McCaw — a combo guard — plugged the hole at starting small forward. It was a big opportunity for a player whom the front office hopes will be a foundational piece of the franchise’s future.

Instead of making significant strides in an expanded role, McCaw simply ate up minutes for the most part during those five-plus weeks Durant missed. McCaw’s averages in 20 regular-season starts — 6.3 points, 2.4 rebounds, 1.9 assists and 23.4 minutes — were adequate given that he started alongside at least three All-Stars, but coaches wanted more. His 47.2 percent shooting in those starts suggested that he could stand to be more aggressive.

On Wednesday, three days after he logged just 23 seconds in Game 1, McCaw overcame a few early misses for perhaps his best all-around outing yet. In addition to protecting the ball and making three shots, he played solid defense on guards Damian Lillard and C.J. McCollum. Midway through the third quarter, on a Lillard layup attempt, McCaw slid into the key for a highlight-worthy block.

“That might have been the best game I’ve seen Pat play,” Warriors guard Klay Thompson said. “He was aggressive from the jump, and he did it on both ends. He’s very athletic attacking the rim, and he has some of the best hands on defense.”

The Warriors’ hope is that extended runs like Wednesday’s will prepare McCaw for more consistent minutes moving forward. After re-signing Durant and Curry this summer, Golden State will have little money left to bring back free agents such as Iguodala, Shaun Livingston and Ian Clark. McCaw, who has a two-year, minimum-salary deal, might be the Warriors’ third guard next season.

In the third quarter Wednesday, after he drove past McCollum for a layup, McCaw barked at a nearby referee about a non-call. From the bench, Green chuckled at the exchange. After more than half a year watching the player known as “P-Nice,” Green appreciated McCaw raising his voice.

“That’s actually the first time I’ve ever seen him show any emotion, so that was pretty good,” Green said. “He was great.”